wrote:

Don't install bottom drains.

Why? 2 main reasons:

1. You have to cut a hole in the bottom of the rubber liner to fit the
drain pipe. No matter how well you plan this and use the top of the
line sealants, it will leak. Maybe not in the first 2-3 years, but no
matter the claims of sealants, they expand and shrink as the
temperature changes and do not change exactly at the same rate as the
rubber liner. Over time this connection fails.

Do you have _any_ evidence to back this up? Consider that the average
toilet seal, generally a much weaker seal than a good gasket in the bottom
of a pond, can last thirty years...

2. The holes in the bottom drain cover plate get clogged up with leaves
and debris. Let's say that the wind blows a plastic bag into your pond
and then the bag eventually falls to the bottom and obstructs the
drain. Now your water pump is sucking into a vacuum and the pump will
burn out.

That can happen. I'm not quite sure how it can be avoided with _any_ pump
though. No matter what system you use, the pump has an intake that can be
clogged.

Also God forbid, but let's say a child is
wading in the pond and slips into the deep end where the drain is. If
his bare leg comes up to the drain it can create a very tight holding
force and actually prevent him from coming up for air. The suction
pressure is so great that even a strong man would need to struggle to
break loose.

Oh, please. Again, that's no different for any pump, but you're talking
about swimming pool-sized pumps. The typical 5000gph pond pump is not
that strong.

We have found that for residential installations the Savio skimmer
http://www.pondkoi.com/pond_products_pond_skimmers.htm works best.

Yeah. Just more commercial spam. In fact, most people who use bottom
drains recommend a skimmer too.

You can visit your pond once a week and scoop out anything that has
settled to the bottom and be done with it in 5 minutes or less.

The whole point of a skimmer is that it should _prevent_ things settling to
the bottom.
--
derek